Wyniki 11-11 spośród 11 dla zapytania: authorDesc:"BOŻENA ŁOSIEWICZ"

Characterization of low-temperature nitrided NiTi shape memory alloy DOI:10.15199/28.2019.3.3

  1. INTRODUCTION Shape memory alloys (SMAs) belong to a class of the shape memory materials, which posses ability to “memorise" or retain their previous form when subjected to certain stimulus such as thermomechanical or magnetic variations. Due to their unique and superior properties, SMAs have drowned significant attention and interest in recent years in broad range of commercial applications. Especially, well-known in this field is nickel-titanium alloy (NiTi), which is also known as NiTiNOL. Invented by William Buehler and Frederick Wang in 1962 NiTi alloy has found wide engineering and technical applications in numerous commercial fields, such as: consumer products, automotive, aerospace, mini actuators, micromechanical systems, robotics and biomedical [1, 2]. In field of aerospace, a family of high force release devices called the “Frangibolt¨, an array of fast acting Pinpullers, a range of innovative Ejector Release Mechanisms (ERMs), and a host of other SMA Actuators have been known [3]. The NiTi-based shape memory alloys are preferable for most of these applications due to their high mechanical and corrosion properties as well as the stability of the effect. However, there are some application areas that require improvement in surface hardness as well as an abrasion resistance. Therefore, studies were done in order to improve these properties through the use of various method of surface treatment, which form e.g. layers of titanium oxide, titanium nitride, carbon coatings such as DLC (diamond like carbon) or NCD (nanocrystalline diamond) and ceramic layers. The methods include: electrochemical oxidation, ion implantation, RFCVD, glow discharge and laser treatment [4÷11]. The limitation in the application of these surface treatments is the temperature of the process, which may negatively affect the shape memory effects [5, 11]. The most of these methods, e.g. nitriding, have been carried out at high tempera[...]

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